Alisdair Cusick By Alisdair Cusick 4 weeks ago

How to fix Porsche 993 Cabriolet roof issues

Is your Porsche 993 Cabriolet roof misbehaving? Weissach UK's Tom Atherton runs 9WERKS through the problems that can arise, plus how to fix them

With summer upon us, owners of Cabriolet models will be itching to enjoy roof-down motoring. For owners of 993 Cabriolets, that could mean discovering an issue. Cheshire independent Weissach UK’s Tom Atherton tells 9WERKS of the problems that can present when dropping the roof on a 993 Cab, and how to prevent them.
“We’re just starting to see issues on 993 Cabriolets,” explains Tom. Not on every car, but certainly some. Within the roof gearboxes is a copper bearing, much like a big end bearing in an engine. “As those wear through, they end up binding,” says Atherton, causing the hood to judder or bind in operation. Weissach’s fix is to machine replacement bearings using a harder grade material, then replace the failed originals using a press, for £190+VAT per side. “There’s two gearboxes, so if one is failed, the other is likely to be equally worn” says Tom.

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    Here's the Cabriolet's gearbox in situ, which is known to wear
    There are microswitches that control the latching mechanism, which can also cause issues. Checking those involves stripping trim to get to the switches, then activating the roof “to check they actually do what they are supposed to do,” says Atherton. Bad ones will mean the motor doesn’t activate or deactivate at the right time, with the fix being a simple replacement microswitch.
    The roof control module isn’t a fully printed circuit board design, instead relying on many soldered components. “If there is room for flex, there is room for failure,” reveals Atherton, explaining the flex can cause dry joints, with one end of a component hanging in air rather than passing current through solder. Weissach offer either a factory replacement part at £350+VAT, or a US-made replacement using modern solid state components, for around £1,000 by the time it is on UK soil. “That’s a great fix, but for a failure that happens over 30 years, say, you have to assess which route it is right for you,” suggests Tom.
      The inside of a 993 Cabriolet's roof gearbox mechanism
      To maximise reliability and longevity of a 993 roof, Atherton advises storing it with the hood up. “This keeps tension on the roof, whereas if you leave it down, or only drive with the hood down, it can cause unsightly rubbing marks on the material. People also forget there’s a service schedule on the roof itself, so it is important to keep it clean, remove dirt, reproof it. Preventative work makes it last.”
      For owners with issues, Weissach prefer to have the car in and go through the whole system. “The roof is difficult to time properly and set up so that both sides operate as one,” Atherton says, adding, “we like to make sure each side [of the roof] is in good health and working as it should.”
      As with any 911, the key to reliability is to be proactive in catching issues. With the correct advice on storing it, plus Weissach UK‘s pointers on identifying issues, you should be able to keep your 993 roof in top form, ensuring sun-in-your-face flat-six motoring is always on hand.
      For more information on Weissach UK’s services for classic and modern Porsche, visit the website or call 01606 834460.

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